Welding is a metal joining process in which two pieces of metal, touching each other, are melted at the edges by a welding gun to fuse them together. When the metals cool down, a strong bond is created. Welding can be done by using either pressure or by using a filler material. The heat can be provided by an electric arc, a gas flame, laser, electron beam, ultrasound, the electrical resistance of the metals, through a chemical reaction, or other methods. Types of welding processes such as spot welding, mig welding, TIG welding, seam welding, projection welding, gas welding, resistance welding, induction welding, thermal welding, and forge welding, etc. can be utilized.
Almost all types of metals such as: iron, steel, aluminum, brass, nickel, phosphor bronze, and tantalum, etc. can be welded by at least one of the processes. Some types of thermoplastics can also be welded.
Arc welding uses a power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. Either direct current (DC) or alternating (AC) current may be used. The process of arc welding is widely used because of its low capital and running costs.
In an arc welding circuit, the work-piece is generally held at or near ground potential while the arch electrode is maintained at a positive electric potential with respect to the work-piece. Electric discharge between the electrode and the work-piece occurs and the arc is defined.
The ground welding cable is connected to the work-piece by a ground clamp. For an arc welding process to function, there must be a sufficient ground (conductivity) between the ground clamp and the work-piece. Otherwise no electric arc circuit will be established. Depending on the work-piece, work environment, and other factors, it is often difficult to establish sufficient ground. Paint, oil, dirt, rust, moisture, and/or elements present on the work-piece or in the word environment factors often interfere with the conductivity of the work-piece so that sufficient ground is not established.
Lack of sufficient ground can cause the welding apparatus to shut down. Such a shut down can occur while the welder is welding, causing the welder to have to reset the ground clamp. Often, the ground clamp must be positioned at a substantial distance from the position where the weld must be made, making resetting the clamp highly inefficient.
With existing ground clamps, there is no way for the welder to know whether sufficient ground has been established before attempting to weld. Through experience, welders develop a knack for avoiding areas with rust, moisture, paint, dirt, and the like.
In addition to arc welding, determining whether sufficient ground exist is necessary for the related process of plasma cutting. Plasma cutting is a process that is used to cut steel and other metals (or sometimes other materials) using a plasma torch. In this process, an inert gas (in some units, compressed air) is blown at high speed out of a nozzle; at the same time an electrical arc is formed through that gas from the nozzle to the surface being cut, turning some of that gas to plasma. The plasma is sufficiently hot to melt the metal being cut and moves sufficiently fast to blow molten metal away from the cut.
An accurate and efficient way to assess whether sufficient ground exists will also aid in plasma gouging. Plasma gouging is a related process, typically performed on the same equipment as plasma cutting. Instead of cutting the material, plasma gouging uses a different torch configuration (torch nozzles and gas diffusers are usually different), and a longer torch-to-work-piece distance, to blow away metal. Plasma gouging can be used in a variety of applications, including removing a weld for rework. The additional sparks generated by the process requires the operator to wear a leather shield protecting their hand and forearm. Torch leads also can be protected by a leather sheath. This extra equipment may have to be taken on and off if the user finds he has not established sufficient ground.
Therefore, there exists a need for a ground clamp capable of indicating whether sufficient ground has been established immediately, consistently, and accurately.